The present invention relates to a measurement device, a filter generation device, a measurement method, and a filter generation method.
Sound localization techniques include an out-of-head localization technique, which localizes sound images outside the head of a listener by using headphones. The out-of-head localization technique localizes sound images outside the head by canceling characteristics from the headphones to the ears and giving four characteristics from stereo speakers to the ears.
In out-of-head localization reproduction, measurement signals (impulse sounds etc.) that are output from 2-channel (which is referred to hereinafter as “ch”) speakers are recorded by microphones (which can be also called “mike”) placed on the listener's ears. Then, a head-related transfer function is calculated based on impulse response, and a filter is generated. The generated filter is convolved to 2-ch audio signals, thereby implementing out-of-head localization reproduction.
Patent Literature 1 (Published Japanese Translation of PCT International Publication for Patent Application, No. 2008-512015) discloses a method for acquiring a set of personalized room impulse responses. In Patent Literature 1, microphones are placed near the ears of a listener. Then, the left and right microphones record impulse sounds when driving speakers.